IL15RA is a cytokine receptor that specifically binds IL15 with high affinity. It shares two subunits with the receptor of IL2, the IL2R beta and IL2R gamma chains. This forms the basis of many overlapping biological activities of IL15 and IL2. The IL2 receptor requires an additional IL2-specific alpha subunit for high affinity IL2 binding. This protein is structurally related to IL2R alpha, but is capable of binding IL15 with high affinity independent of other subunits, which suggests the distinct roles between IL15 and IL2. This receptor is reported to enhance cell proliferation and expression of apoptosis inhibitor BCL2L1/BCL2-XL and BCL2. There are nine different isoforms.